Devices of the above mentioned kind are known and are primarily intended to be used for jetting droplets of viscous medium, e.g. solder paste or glue, onto a substrate, e.g. an electronic circuit board, prior to mounting of components thereon. An example of such a jetting device is disclosed in WO 99/64167. The jetting device comprises an eject chamber for containing a small volume of said medium prior to the jetting thereof, an eject nozzle communicating with the eject chamber, eject means for jetting said medium from the eject chamber through the eject nozzle, and supply means for feeding said medium into the eject chamber. In WO 00/62587 there is disclosed an assembly comprising such a jetting device.
The production speed is an essential factor in the manufacturing of electronic circuit boards. This has lead to a desire of increasing the speed at which a substrate is provided with viscous medium, a way of effecting this is to perform the actual jetting “on the fly”, i.e. without stopping for each location on the substrate where viscous medium is to be deposited. A further way to improve the manufacturing speed of electronic circuit boards is to eliminate or reduce the need for operator interventions.
Both of these measures require good and reliable performance of the device used in the process, as well as a high degree of accuracy and a maintained high level of reproducibility during an extended period of time. The high quality requirements of the electronic industry and the detrimental consequences of errors appearing in circuit boards even further emphasise these requirements.